with multiple cameras I'm not sure
you'll have to get software to flip automatically from one camera to another

if you want separate video streams for each camera then each feed will get encoded separately

there are network/IP cameras that can pan/tilt remotely by users but they'll run you $500-$1000 each

Either way you'll probably have to have your own server on premise then pipe the video out via dedicated T1 connection or fiber if your municipality has that near you - last mile fiber - and out to a CDN or some other host or your own server.

You can do pure CDN (content delivery network) where bandwidth is clean.

Or get stream hosting, that does Flash/WIndows media streaming and could give you X concurrent users watching @___Kbps each for $..../month or unlimited.

http://www.egihosting.com/stream_hosting_specials.aspx

I believe StreamingMedia.com recently mentioned someone on 250TB traffic contract getting bandwidth for something like $0.07/GB with a CDN network.

With a CDN you'll probably have to lock yourself in at least a 1yr contract

Leo Laporte who's doing tech podcasts bought a Mac server for around $4-$5k that does the video encoding and then pipes the video out via last mile fiber for $700/month at 9Mbps or 12Mbps symmetrical to a Bitgravity server which then lets everyone watch the live video feed in a embeddable flash player.

Alternatively you could spend $ on the set up and dedicated internet connection then stream to Ustream, Qik, JustinTV etc which are free (with ads)